Arkham Asylum is in ruins. Gotham's new mayor has a radical concept to take its place: Arkham City, a walled city-within-a-city to house the most dangerous criminals alive. While its new inhabitants conspire to control it, Batman is determined to unveil the mastermind behind this dangerous idea.It's been a year since The Joker took over Arkham, and Gotham is still trying to get back to normal in this all-new, 5-issue miniseries bridging the gap between the hit videogame Batman: Arkham Asylum and the exciting, upcoming sequel, Batman: Arkham City! And now, an attack by a pair of super-powered twins increases the threat level and triggers Gotham City's new mayor to call for drastic measures.Amid the protests of both human rights groups and Bruce Wayne, a new Arkham rises. The Joker is scheduled to be its first inmate, but not if Harley Quinn has anything to say about it. Meanwhile, Batman's suspicions lead him to investigate just who is really behind this new, sprawling prison and what their motivations might be. The Joker and Harley are setting up their new love nest in the old Sionis Steel Mill. An unknown street thug boldly offers his services and is put to a deadly test. Later, he decides to see what The Penguin has to offer. What dangerous game is this mysterious figure playing? The gates swing shut on Arkham City, trapping small-time criminals and deadly Super-Villains behind its walls. Batman finds himself on the side of his greatest foes, as he fights to save Gotham City from within its diseased heart.The miniseries that leads you into the video game comes to its dramatic conclusion! The die is cast and the criminal gulag known as Arkham City is now in place. But even with its imposing walls and security measures, is anyone in Gotham City really going to feel safe with a legion of criminals living next door?